Dermatome with a reciprocable knife

ABSTRACT

The dermatome includes a knife assembly for cutting away a skin transplant, reciprocable along guides mounted in the housing. The knife is operatively connected through a connecting rod with an eccentric crank means associated with a drive shaft extending through the handle. To counterbalance the forces generated by the reciprocation of the knife assembly in operation and capable of vibrating the housing, a counterweight is provided which is reciprocable along the guides in the direction that is always opposite to that of the motion of the knife assembly. The dermatome further includes means for limiting the width of the skin transplant being cut away and means for adjusting the thickness of the skin transplant being cut away.

United States Patent Vanjushin et a1.

[ DERMATOME WITH A RECIPROCABLE KNIFE [76] Inventors: Sergei Petrovich Vaniushin,

Zvezdny bulvar 30, korpus 1, kv. 46; Leonid Fedorovich Bandakov, Urzhumskaya ulitsa, 3, korpus 3, kv. 366, both of Moscow, USSR.

[11] 3,826,543 June 28, 1974 3,583,403 6/1971 Pohl et a1 128/305 Primary ExaminerChanning L. Pace Attorney, Agent, or FirmHolman & Stern [57] ABSTRACT The dermatome includes a knife assembly for cutting [22] Filed: July 14, 1972 away a skin transplant, reciprocable along guides mounted in the housing. The knife is operatively con- [211 Appl 27l651 nected through a connecting rod with an eccentric crank means associated with a drive shaft extending [30] Foreign Application Priority Data through the handle. To counterbalance the forces gen- Oct I5 1971 u.s .s R 1705274 erated by the reciprocation of the knife assembly in operation and capable of vibrating the housing, a 52 us. Cl. 128/305, 30/394 counterweight is Provided Whieh is teeipteeahie along 51 Int. Cl A6lb 17/322 the guides in the diteetieh that is always Opposite to 5 Field of Searchm' 30/392 394- 129/305 3055 that Of the motion of the knife assembly. The dermatome further includes means for limiting the width of [56] References Cited the skin transplant being cut away and means for ad- UNITED STA-TBS PATENTS jllStlIlg the thickness of the skin transplant being cut awa 2,457,772 12/1948 Brown et a1, 128/305 y I 1 2,639,737 5/1953 Forsberg 30/392 4 Claims, 7 Drawing Figures U l6 l4 19 E 5 t I] 6 Z PATENTED JUN 2 8 I974 SHEET 1 [IF 3 DERMATOME WITH A RECIPROCABLE KNIFE BACKGROUND OF THE INVENTION The invention relates generally to a surgical apparatus, and, more particularly, it relates to dermatoms having reciprocable knives.

The invention can be advantageously employed for cutting skin transplants of a relatively great width for plastic surgery purposes, e.g. in cases of large burns.

Dermatomes are known in the prior art. For example, a known dermatome has a bail-shaped housing incorporating guides in the form of pins. A knife with a specially-designed replaceable blade is reciprocable along centric crank means associated with the drive shaft.

being cut away and means for limiting the width of the transplant being cut away. The transplant thickness adjusting means includes a movable member adapted to vary the'size of the gap above the knife, relative to the transplant being cut away. The means for limiting the width of the skin transplant are mounted on the guide pins which are disposed in front of the knife and in the front portion of the housing. A spindle is mounted between the pins having two sets of threads of opposite spiral, the two portions meeting at the center of the spindle. Each one of the two transplant width limiting means moves along its respective thread. One of the ends of the spindle projects exteriorly from the housing and carries a handle by means of which the spindle can be manually rotated in order to adjust the two transplant width limiting means symmetrically and simultaneously.

This known dermotome displays in its operation considerable housing vibration, due to the reciprocating motion of the knife. The vibration of the housing affects the conditions of the transplant being cut away, and, consequently, brings down the productivity of the dermotome and hampers the quality of the transplant, namely, the transplant is apt to have uneven thickness and even local perforations. The productivity of this dermatome is usually expressed as-the area of skin transplant cut away per unit of time.

With the rotary speed of the drive shaft being relatively high 2,000 rpm to 3,000 rpm the known dermatome has a relatively short operational life, due to the rapid wearing away of the area of engagement of the eccentric crank with the bifurcated driving member of the knife. The wearing away of the eccentric crank results in greater noise and makes the vibration of the housing, as great as it has already been, still greater. Furthermore, simultaneous and symmetrical adjustment of the transplant width limiting means relative to the center of the spindle makes it impossible to cut a skin transplant from donor skin areas having an obstructed access.

Other dermatomes are also known in the prior art which also have a reciprocable knife. This dermatome has a bail-shaped housing incorporating guiding pins. A knife is reciprocable along the pins, the knife being op- The latter is journaled in bearings within of the handle. The connecting rod transforms the rotation of the drive shaft into reciprocation of the knife. This dermatome also has means for adjusting the thickness of the transplant being cut away and means for limiting the thickness of the transplant. The transplant thickness adjusting means is in the form of a movable member adapted to vary the size of the gap above the knife relative to the transplant being cut away. The skin transplant width limiting means are mounted on the guiding pins mounted in front of the knife, and in the front portion of the housing. Mounted between the guiding pins is a spindle having two portions with threads of opposite spiral, the two portions meeting at the center of the spindle. Each one of the two transplant width limiting means is internally threaded and is movable along the one of the two respective threaded portions of the spindle. One end from the spindle projects exteriorly of the housing where it has mounted thereon a handle by means of which the two skin transplant width limiting means can be displaced.

In this last-described known dermatome vibrations are reduced due to the reduced width of the knife, since it is understandable that the wider the knife, the greater its mass, and, consequently, the greater are the inertia forces increasing the amplitude of the housing vibration, brought about by reciprocation of the knife. However, with the dermatome constructed in this manner the vibration of its housing is merely reduced, but not eliminated. Besides, this last-described dermatome offers limited cutting width of the transplant being cut away. It is capable of cutting away a transplant not wider than 60 mm.

Another known dermatome has a housing with a solid body having guiding grooves cut therein along which there is a reciprocated knife operatively connected to the eccentric crank associated with the drive shaft. The knife has a relatively small profile plate to which an especially designed blade is soldered. The dermatome also has means for adjusting the thickness of the skin transplant being cut away, and a pair of means limiting the width of the transplant. The means limiting the width of the skin transplant being cutaway are in the form of two bent plates fixed to the bottom part of the housing, relative to the skin transplant being cut away.

In this known dermatome vibration the housing is considerably reduced due to the great difference between the weight of the housing and that of the knife. However, it is incapable of cutting away skin transplants of relatively great width, e.g. those needed in cases of large burns. The width of a transplant it is capable of cutting away is about 50 to 55 mm. Operation of this dermatome is impeded by the fact that when the blade gets blunt the whole knife is discarded.

SUMMARY OF THE INVENTION It is an object of the present invention to increase the operation productivity of the dermatome by improving the conditions of cutting away a skin transplant, namely, by eliminating vibrations of the dermatome.

With this and other objects in view, the essence of the present invention resides in a dermatome having a reciprocable knife, comprising a housing with guides along which the knife can be reciprocated, the knife being operatively connected through a connecting rod with an eccentric crank associated with a drive shaft extending through a handle, the dermatome further having means for adjusting the thickness of the skin tranplant being cut away and means limiting the width of the skin transplant being cut away, in which dermatome, in accordance with the invention, there is provided a counterweight movable along the guides in a direction opposite to that of the motion of the knife.

In a dermatome constructed in the abovedescribed way housing vibrations are completely eliminated due to the moving masses being counterbalanced, whereby the forces generated by the reciprocation of the knife and capable of bringing about housing vibrations are counterbalanced, too. With the dermatome vibrations completely eliminated, the conditions for cutting away a skin transplant are improved, which results in increased quality of transplant, and increased productivity of the dermatome and, hence in reduced time of plastic surgery operations. As it has been explained hereinabove, the productivity of a dermatome is expressed as the area of a skin transplant cut away per unit of time.

It is advisable that the counterweight should be disposed downward from the knife, relative to the surface from which the skin transplant is being cut away.

With the counterweight thus arranged, it can be easily received within the overall dimensions of the knife, whereby it can be reciprocated along the same guides that are used for reciprocation of the knife itself. In this way the structure of the dermatome is simplified. Besides, the arrangement of the counterweight under the knife simplifies the task of the plastic surgeon during surgery, because the transplant that has been cut away freely leaves the exit gap and can be easily taken by the surgeon.

It is further advisable that reciprocation of the counterweight should be effected by a connecting rod operatively connected with the eccentric crank associated with the drive shaft.

Preferably, the eccentric crank associated with the drive shaft is in the form of a crankshaft with two crankpins arranged in diametn'cal opposition to each other, relative to the axis of rotation of the drive shaft, one of the two crankpins being operatively connected to the knife and the other one being operatively connected to the counterweight.

The operative connection of the counterweight to one crankpin to the eccentric crank and of the knife with the other crankpin results in a counterbalancing action for the moving masses, and, consequently, of the forces generated by reciprocation of the knife which are capable of bringing about housing vibrations, whereby vibrations of the housing are positively eliminated.

It is advisable that the counterweight be in the form of a plate having a mass equal to the mass of the knife.

With the counterweight being in the form of a plate, it can be arranged under the knife, relative to the skin transplant being cut away, and can be received within the overall dimensions of the knife.

In a dermatome having a reciprocable knife, constructed in accordance with the invention, housing vibrations are completely eliminated, whereby the dermatome operates noiselessly, the conditions for cutting away a skin transplant are improved, as with as the quality of the transplant itself; the dermatome glides smoothly over the donor skin area (i.e. the area from which the transplant is being cut away); the thickness of the transplant is adjustable from 0.1 mm to 1.0 mm, and the width thereof can be great as I00 mm, e.g. in cases of large burns. The productivity of the dermatome during a transplant cutting operation has been increased from two to 2.5 times, as compared with the hitherto known dermatomes.

The dermatome is simple and reliable in operation. The knife of the dermatome may employ elongated blades such as the type used in safety razors.

The dermatome may be operated from alternatingcurrent supply it may be powered by an electric motor rated at 220 Volts, the shaft of the motor making 2,700 revolutions per minute and the knife making, 5,400 strokes per minute.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects and advantages of the present invention will become apparent from the following description of the embodiments thereof, with reference to the appended drawings, wherein:

FIG. 1 is a partly broken away schematic side view of a dermatome with reciprocable knife, constructed in accordance with the invention;

FIG. 2 is a smaller-scale plan view of the dermatome, constructed in accordance with the invention;

FIG. 3 is a cross-sectional view taken along line III- III of FIG. 2;

FIG. 4 illustrates the knife and the counterweight of the dermatome, constructed in accordance with the invention;

FIG. 5 is a view taken along line A of FIG. 4;

FIG. 6 is a plan view of the support bar and of the skin transplant width limiting means of the dermatome constructed in accordance with the invention; and

FIG. 7 is a smaller-scale front view of the dermatome constructed in accordance with the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now in particular to the appended drawings, a dermatome comprises a bail-shaped housing 1 (FIGS. 1 and 2) having thereinside a support bar 2 and a base member 3 (FIG. I Guides 4 are fixed inside the housing 1 and are in the form of guiding pins. A knife 5 is reciprocable along these guides 4. The knife 5 is an assembly including a backing plate 6 (FIG.3) integral with a slide 7 and projections 8 receiving thereon a replaceable blade 9, the backing plate further having projections 10 on which is mounted a retaining plate 11. A retaining screw 12 (FIG.2) is provided on the backing plate 6 to clamp the blade 9 (FIG.3) between the backing plate 6 and the retaining plate 11. The blade 9 is preferably in the form of three unsevered safety razor blades. Downward from the knife 5, relative to the surface from which a transplant is to be cut, there is provided a counterweight l3 (FIG.4). The latter is adapted to travel along the same guides 4 (FIGS) in a direction opposite to that of the motion of the knife 5. The counterweight 13 is in the form of a panel the mass of which is equal to that of the knife 5. With the counterweight 13 being positioned downwardly of the knife 5, the skin transplant being cut away is free to leave the dermatome, which facilitates the performance of plastic surgery.

A handle 14 is connected to the central portion of the housing 1 by a threaded connection 16. Passing internally throught the handle 14 is a drive shaft 16 (FIGS) journaled in ball bearings 15, the shaft having an eccentric crank 17 mounted in the threaded opening thereof. The eccentric crank 17 is in the form of a crankshaft having a pair of crankpins 18 and 19 disposed in diametrical opposition to each other relative to the axis of rotation of the drive shaft 16. The crankpin 18 of the eccentric 17 is pivotally connected to one end of a connecting rod 20. The other end of the connecting rod 20 is pivotally connected to the backing plate 6 of the knife assembly 5.

The crankpin 19 of the eccentric crank 17 is pivotally connected to one end of the connecting rod 21. The other end of the connecting rod 21 is pivotally connected with the counterweight 13.

The herein disclosed dermatome includes a means 22 (FlG.2) for adjusting the thickness of a skin transplant to be cut away, as well as a means 23 for limiting the width of the transplant being cut. The thickness adjusting means 22 are disposed centrally of the support bar 2 having marked thereon a linear scale 24 (FIG.6) calibrated in units of the width of the skin transplant being cut away and a dial 25 calibrated in units of the thickness of the skin transplant being cut away.

The linear scale 24 not only provides for presetting the means 23 limiting the width of the transplant, but also for measuring the length of the transplant, in which case the scale 24 is used as a ruler, with both width and length measurements being necessary for determining the total area of the skin transplant being cut away during the course of plastic surgery. The thickness adjusting means 22 (F161) is associated with a limiting rounded strip 26 mounted in cantilever fashion on arms 27 pivoted on one of the guides 4. The rounded strip 26 has a screw 28 pivotally mounted thereon engaging the head 29 of the thickness adjusting means 22.

The rounded strip 26 and the blade 9 (FIG.3) of the knife assembly 5 define a gap therebetween through which the skin transplant that has been cut away leaves the dermatome. The size of this gap determines the thickness of the transplant that is being cut away.

. The transplant width limiting means 23 (FIGS. 3 and 6) are mounted on the support bar 2, each one of the two limiting means 23 having a groove cut therein complementary to the cross-sectional shape of the bar 2 With the transplant width limiting means 23 being mounted on the support bar 2, an unobstructed view is offered to'the skin area from which the transplant is being cut away by the operation of the knife assembly 5. The two transplant width limiting means 23 can be independently adjusted longitudinally with respect to the support bar 2, whereby it is possible to cut away skin transplants not only with the central portion of the blade, but also with the edge portions thereof which becomes essential in cases of skin areas having obstructed access, as well as in cases of necroctomy.

A leaf spring 30 is inserted into the clearance intermediate of the support bar 2 and the adjacent internal wall of each one of the width limiting means 23 which facilitates the setting with respect to the limiting means 23 longitudinally of the support bar 2.

The surfaces of the herein disclosed dermatome, en-

' gaging the donor skin area in operation, namely, the

base member 3, the limiting rounded strip 26 and the means 23 limiting the width of the transplant, have fluted portions 31 (FIGS. 3 and 7) preventing displacement of the skin during the course of the cutting operation.

The herein disclosed dermatom for cutting away skin transplants operates as follows.

The head 29 (FlG.l) of the transplant thickness adjusting means 22 is rotated to preset with the help of the dial 25 (FlG.6) to a desired thickness of the transplant to be cut. The transplant width limiting means 23 are independently adjusted along the bar 2 and are set either symmetrically relative to the central axis of the dermatome, or at different spacing therefrom, depending on the position of the donor skin area on the body.

The width of the transplant to be cut away is read on the scale 24 of the support bar 2 individually for each one of the two width limiting means 23. The total width of the transplant is the sum of the readings pertaining to the two width limiting means 23. A remote electric motor (not shown in the drawings) is energized to effect rotation of the drive shaft 16, which rotation is transformed into reciprocation action of the knife assembly 5 with the help of the connecting rod 20 pivotally connected to the crankpin 18 of. the eccentric crank 17 of the drive shaft 16, as well as into reciprocation action of the counterweight 13 with the help of the connecting rod 21 pivotally connected with the other crankpin 19 of the eccentric crank 17. The counterweight 13 always moves in opposition to the motion of the knife assembly 5. When the knife assembly 5 is thus reciprocated, a skin transplant may be cut away.

The motion of the counterweight 13, opposing that of the knife assembly 5, brings about a balancing action of the moving masses, and, consequently, of the forces generated by reciprocation of the knife assembly 5 which would be capable of vibrating the housing 1 of the dermatome. Any vibration of the housing 1 of the herein disclosed dermatom is thus positively prevented.

Consequently, a noiseless operation is ensured for the dermatome; the cutting performance thereof is improved, together with the quality of the transplant; and the dermatome becomes capable of gliding smoothly over the donor. skin area.

What is claimed is:

1. A dermatome having a reciprocable knife, comprising: a housing having guide means mounted therein; a knife for cutting away a skin transplant reciprocable along said guide means; a counterweight for counterbalancing the forces generated by the reciprocation of said knife which are capable of bringing about vibrations of said housing; said counterweight being adapted for reciprocation along said guide means in a direction that is opposite to that of the motion of said knife; a handle mounted on said housing for facilitating operation of said dermatome during a skin transplanting operation, a drive shaft extending through said handle and being in the form of a crankshaft having crankpins disposed in diametrical opposition to each other relative to the axis of rotation, one of said crankpins being connected to said knife and another of said crankpins being coupled to said counterweight for transforming rotation of said drive shaft into reciprocation of said knife and said counterweight; means for limiting the width of the skin transplant being cut away; and means for adjusting the thickness of the skin transplant being cutaway by varying the size of a gap through which the skin transplant that has been cut away leaves said dermatome.

2. A dermatome as claimed in claim 1 wherein said counterweight is disposed under said knife relative to the surface from which the transplant is being cut away.

3. A dermatome as claimed in claim 1 wherein the reciprocation of said counterweight is effected by equal to'the mass of said knife. 

1. A dermatome having a reciprocable knife, comprising: a housing having guide means mounted therein; a knife for cutting away a skin transplant reciprocable along said guide means; a counterweight for counterbalancing the forces generated by the reciprocation of said knife which are capable of bringing about vibrations of said housing; said counterweight being adapted for reciprocation along said guide means in a direction that is opposite to that of the motion of said knife; a handle mounted on said housing for facilitating operation of said dermatome during a skin transplanting operation, a drive shaft extending through said handle and being in the form of a crankshaft having crankpins disposed in diametrical opposition to each other relative to the axis of rotation, one of said crankpins being connected to said knife and another of said crankpins being coupled to said counterweight for transforming rotation of said drive shaft into reciprocation of said knife and said counterweight; means for limiting the width of the skin transplant being cut away; and means for adjusting the thickness of the skin transplant being cut away by varying the size of a gap through which the skin transplant that has been cut away leaves said dermatome.
 2. A dermatome as claimed in claim 1 wherein said counterweight is disposed under said knife relative to the surface from which the transplant is being cut away.
 3. A dermatome as claimed in claim 1 wherein the reciprocation of said counterweight is effected by means of a connecting rod operatively connected to said drive shaft having an eccentric crank mounted therein.
 4. A dermatome as claimed in claim 1 wherein said counterweight includes a panel having a mass thereof equal to the mass of said knife. 